ajdelange - your alkalinity eq. doesn't take the ions from the grist into consideration. But it works awesome for a beaker of water and some salts.

Thanks for the compliment but that equation is attributable to Kolbach - not me. You can find a translation of his paper at www.wetnewf.org (Kolbach's 1953 paper). While the 0.17 increase in pH per increase of 100 ppm as CaCO3 he observed (he actually observed in dH) is approximate it does take into account the buffers in malt. In fact it is a sort of measure of the buffering capacity of pure base malt grists.

Quote:

Originally Posted by funkswing

I can't give you eq. to back up my claims. Its empirical data. 3 g CaCO3 in 5 gal mash isn't going to raise the pH with my (soft, city) water. Those grains have buffering capacity, that's why your pH drops when you mix it with the water.

If you are seeing a drop in pH when you add calcium carbonate to mash then you are measuring pH wrong. The grains do, of course, contain buffering systems but if you stress a buffer with alkalai (carbonate) pH goes up, not down. For a rather detailed explanation go to the same website and download the article "Cerevesia 2004" which goes into the phosphate and carbonate chemistry involved in this process. If you do that you will find that the main mechanism by which calcium lowers pH is precipitation of hydroxylapatite

10Ca++ + 6(PO4–--) + 2H2O ↔ Ca10 (PO4 )3(OH)2 + 2H+

in which 10 moles of calcium precipitated releases 2 moles of hydrogen ions. Approximately 12 more moles of hydrogen ions are released as monobasic inorganic phosphate from the malt is converted first to dibasic and then tribasic phosphate for a total of 14. If the calcium comes from calcium carbonate 10 moles of calcium imply 10 moles of carbonate which require a bit less than 20 moles of hydrogen ion to lower the pH to desired mash pH. Thus there is a deficit of 0.6 mole of H+ for each mole of calcium precipitated and mash pH goes up. This is a gross simplification but the Cerevesia paper shows some results of simultaneous solution of both the carbonate and phosphate buffering systems. Under certain assumptions these models reproduce Kolbach's result. Lots of equations here, yes, but experiment confirms.

You should be aware that it is widely accepted that adding chalk to a mash raises its pH and that many brewers, home and professional, use this means for mash pH adjustment as reference to any of the many water adjustment spreadsheets will show you. While this is true if you put as much as 3 grams of chalk into a 5 gallon mash most of it will not dissolve because there simply isn't enough acid in malt to dissolve that much chalk and even if there were the reaction would be very slow. pH will rise but not to the extent that the stoichimetry might predict.

I have figured the amounts of Calcium Chloride and Calcium Sulfate I need to add for my Pale Ale. I have this amount figured out for 3 gallons of water, 5 gallons, and 10 gallons.

I have 7 pounds of grain, so I'm going to mash with about 11 quarts of water, that'd be about 2.75 gallons. So I can just add the amount of salts I would need for 3 gallons of water to my mash no problem.

My question is--I want to treat my sparge water too so that I can have all the water in my beer have the same profile. I figure I'll sparge with about 5.5 gallons. The goal is to collect about 4 gallons of wort for my 3.5 gallon batch. So I'll need about 10 gallons of treated water (8.25 for mash and sparge plus a little extra if I need to top off, raise temps etc.)

Would it be advisable to treat all 10 gallons of water? I.e. add enough CaCl and CaSO4 for ten gallons of water (in a pot) and let it dissolve? Then I can just use that water how I please?

Or should I add the salts to the mash for 3 gallons and then treat the other 7 gallons separately?

I realize my wording is confusing but what is the best way to go about this so that ALL my water has the same profile (not just the mash).

Cool. Thanks for the advice. I redid my calculations and actually only need 6.75 gallons of water total. 2.75 for mash and 4 for sparging. That total volume of water requires four grams of CaCL and four grams of CaSO4 to get the results I want.

So I think what I'll do is put 1.75 grams of each in the mash, and put the other 2.25 grams in my 4 gallons of water when I heat it to sparge. Mostly just because I don't have a bucket big enough to hold 7 gallons of water. But I'll also feel better knowing that at least my Mash PH will be right if the CaCl and CaSO4 don't dissolve as much as they should, or something weird like that.

Are you using 100% distilled water? Regardless, 4 grams of gypsum is going to be one hell of a bitter beer (the sulfate intensifies bitterness perception). This is from much experience with adding salts, esp. gypsum (its my favorite mineral! not just in terms of brewing).

Are you trying to make Burton on Trent water? What is your goal with the salt additions
(you may want to start a new thread for this question)

Also, gypsum and CaCl2 won't change the pH of water (I guess the additional Ca2+ ions could lower the pH some once mixed with the grist, maybe......)

Are you using 100% distilled water? Regardless, 4 grams of gypsum is going to be one hell of a bitter beer (the sulfate intensifies bitterness perception). This is from much experience with adding salts, esp. gypsum (its my favorite mineral! not just in terms of brewing).

Are you trying to make Burton on Trent water? What is your goal with the salt additions
(you may want to start a new thread for this question)

Also, gypsum and CaCl2 won't change the pH of water (I guess the additional Ca2+ ions could lower the pH some once mixed with the grist, maybe......)

According to Palmers Spreadsheet, those additions should make for a good water profile for my beer. I'm making a Pale Ale at 7 SRM.

It'll bring my minerals to this: Chloride 78, Sulfate 89. RA of -19. Perfectly acceptable for 4-9 SRM beer. That'll be nice and balanced (for the Cl to SO4) and well within the range I need. I'm using 50% distilled and 50% tap.

So according to Palmer's spreadsheet I'm good. I'll get a beer that is dry, sharp, and slightly bitter but still with a nice balance. Also, using the easy water chemistry spreadsheet (found here) it says my Mash PH will be about 5.6.